Modified Method for Propagation of Rift Valley Fever Virus

Trials for propagation of RVFV on Vero cells using different MOI 0.1, 0.01 & 0.001 and different concentrations of trypsin (25 & 50 µg/ml). The result indicated that high titer of RVFV (8.0 log₁₀ TCID₅₀/ml in Vero cells, 7.5 log₁₀ MIPLD₅₀/ml in adult mice and 7.7 log₁₀ MICLD₅₀/ml in baby mice) was obtained with MOI 0.001 using 50 µg / ml of trypsin after 24 hrs post inoculation. Inoculation of freshly subcultured Vero cells as other method lead to obtaining high virus titer (8.5 log₁₀ TCID₅₀/ml in Vero cells, 7.6 log₁₀ MIPLD₅₀/ml in adult mice and 8.2 log₁₀ MICLD₅₀/ml in baby mice) after 48 hours with MOI 0.0001. While using subculture of monolayer Vero cells 24 hours previously infected with RVFV, it was obtained high titer (8.0 log₁₀ TCID₅₀/ml in Vero cells, 7.4 log₁₀ MIPLD₅₀ / ml in adult mice and 7.9 log₁₀ MICLD₅₀/ml in baby mice) with MOI 0.001 as well as a triple amount of virus yielded than the traditional method. Different batches of inactivated RVFV vaccine were prepared from the harvested virus which was identified as RVFV using AGPT. Quality control tests were applied proved that all vaccine batches were sterile, safe and potent. It is concluded that modified methods could increase RVFV production with high titer as well as saving time, saving materials used in virus production include quantity of inoculums.